The present invention relates generally to terminals for entering data. More particularly, the present invention relates to a robust, low-cost keyboard suitable for use in adverse environments.
Some public telephones use a computer-style keyboard to provide data terminal emulation. This allows the public access to e-mail, data bases, the Internet, deaf terminal communication and the like. A keyboard situated in a public environment (xe2x80x9cpublic-use keyboardxe2x80x9d) is typically subjected to substantially more adverse conditions than a keyboard that is used within the home or in a corporate setting. For example, public-use keyboards may be located out-of-doors and thus exposed to the prevailing weather conditions (e.g., rain, sleet, etc.). And, perhaps even more problematic, such public-use keyboards are often vandalized.
Public-use computer-style keyboards are relatively expensive. One reason for the expense is the ubiquitous xe2x80x9csliding-plungerxe2x80x9d key mechanism. The sliding-plunger key mechanism uses, for each key, a plunger, a key cap glued to the plunger, and a spring for providing a restoring force to the plunger. Those three parts, and sometimes more, are required for each of the over one hundred keys on a keyboard. Such a large number of parts represents a significant cost factor for such keyboards.
A second reason for the relatively high cost of such public-use keyboards relates to the use of vandalism-prevention measures. In particular, public-use keyboards are often stored within a mechanized metal drawer. The keyboard is accessible only after a user enters credit card information. The drawer is a relatively expensive item and represents a second significant cost factor for a public-use keyboard.
It would be desirable, especially in view of a relatively short life span, to develop lower cost computer-style keyboards for public use.
An article comprising an improved keyboard in accordance with an illustrated embodiment of the present invention is disclosed. The present keyboard advantageously includes a keyboard membrane having, on an upper side, a plurality of raised regions upon which character designators are disposed. Each of such designated raised regions is analogous to a key cap of a conventional keyboard. A user depresses such raised regions to xe2x80x9ctypexe2x80x9d on the present keyboard.
A plurality of upper key members are disposed on a lower side of the keyboard membrane. One upper key member is disposed directly underneath each one of the raised regions. Each upper key member is structurally adapted to provide a restoring force that, after removal of an actuating force, causes the upper key member to return to an unactuated position.
In some embodiments, the keyboard membrane is formed from a layer of flexible, resilient, elastomeric material. The raised regions on the upper side, and the upper key members on the lower side are advantageously molded from the elastomeric layer so that the keyboard membrane, the plurality of raised regions and the plurality of upper key members may comprise a single part or be divided into a small number of parts comprising different regions of the keyboard. Thus one part or a substantially reduced number of parts may replace over two hundred parts in conventional computer-style keyboards using sliding-plunger type key mechanisms.
A plurality of lower key members are disposed on a circuit board underneath the keyboard membrane. The lower key members are structurally adapted to prevent xe2x80x9crock overxe2x80x9d (i.e., a deviation in the downward path of an upper key member resulting in a mis-strike) when an actuating force is applied off-center on the raised region.
In some embodiments, the present keyboard advantageously includes a wire braid disposed on the keyboard membrane that functions as a flexible armor to protect underlying keyboard elements. The protective braid is physically adapted to engage features of the keyboard membrane whereby the wire braid is securable to the keyboard. Additionally, in some embodiments, the keyboard membrane advantageously includes a seal for preventing liquid (e.g., rain, drink spills, etc.) from penetrating the keyboard housing. Such a seal provides for a substantially liquid-resistant keyboard.